Field of the Invention
The present invention relates to a combustion plate, and more particularly, to a combustion plate with many burner ports formed in the plate body.
Description of the Related Arts
Conventionally, combustion plates with many burner ports formed in a ceramic plate body are used for all primary combustion system type burners provided for heat source equipment for hot water supply, heating or the like.
Various efforts are made in this type of combustion plate to suppress resonance of flames and reduce noise.
For example, Japanese Patent Laid-Open No. 6-147434 describes a combustion plate with many large, medium and small burner ports arranged such that one large burner port is placed at a center of four neighboring small burner ports and each small burner port is placed at a center of four medium burner ports. In this combustion plate, flames of the large burner port with large vibration energy are attenuated by interference of flames of medium burner ports with a medium frequency and vibration energy. Similarly, vibration energy of flames with medium burner ports is attenuated by interference of flames of small burner ports.
Furthermore, Japanese Patent Laid-Open No. 6-147435 describes a combustion plate in which many small burner ports are divided into a main flame group that forms main flames, a first pilot flame group that forms a small pilot flame group around the main flames, and a second pilot flame group that forms a pilot flame array that surrounds each main flame and the first pilot flame group. In this combustion plate, the number of burner ports differs from one burner port group to another, which causes a resonance frequency of flames to differ from one burner port group to another, preventing combustion resonance from occurring.
However, in the combustion plate described in above Japanese Patent Laid-Open No. 6-147434, heat is likely to concentrate on the large burner port and backfire is likely to occur.
In the combustion plate described in above Japanese Patent Laid-Open No.6-147435, flames are likely to resonate in a situation in which flames are formed in individual burner ports instead of set flames of each group.
The present invention has been implemented in view of such a background, and it is an object of the present invention to provide a combustion plate capable of preventing resonance of flames and backfire.